pub fn new_birthday_probability(n: u32) -> f64 {
    if n>365 {
        return 1.0;
    }
    let mut proba = 1.0;

    for i in 0..n{
        proba*=(365-i) as f64/365.0;
    }
    let probb =1.0-proba;
    (probb*10000.0).round()/10000.0 //keep digit
}
